The present invention relates to light guides utilized, for instance, in curing resins in medical, dental, scientific, industrial and military applications. More particularly, the present invention relates to a method of making a fiberoptic light probe useful for producing a concentrated high-intensity light for curing a photocurable dental composition.
Light guides are utilized to expose photocurable materials to high intensity visible light to change the materials from a paste-like putty to a substance having the hardness of ceramic or glass in a few seconds. Thus, for example, such probes have been utilized in dental procedures to harden photocurable sealants, adhesives and filler material for filling dental cavities. Of course, such a probe can be utilized in any application which requires an accurately directed high intensity light beam.
U.S. Pat. No. 4,846,546 issued to Joseph Cuda discloses a fiberoptic light guide useable as a dental probe. The elongate fiberoptic probe has a constant diameter from its proximal end to its distal end, and the distal end is angled at approximately 60xc2x0 from the longitudinal axis of the proximal end of the probe so that a high intensity light beam can be accurately directed within a mouth of a patient during a dental procedure.
As disclosed in the above referenced Cuda patent, the probe is manufactured by inserting a bundle of closely packed elongate and continuous glass rod fibers into a hollow cylindrical glass cladding and then by drawing this assembly into a smaller diameter to create a heat-fused, solid, substantially-cylindrical fiberoptic rod. For example, as disclosed by the Cuda patent, hundreds of fibers can be inserted into a hollow cladding having a diameter of about 40 mm. The assembly can then be drawn to a diameter of about 8 mm throughout its length. The heat fused rod is then cut to length; a distal end of the rod is heated and bent to form a bent tip of the probe; and the ends of the probe are ground and polished. In addition, end fittings can be adhesively secured to the ends of the probe so that, for instance, the probe can be readily connected to a light gun or like high intensity light generating apparatus.
Another fiberoptic dental probe is disclosed in U.S. Pat. No. 5,371,826 issued to Friedman. The Friedman patent discloses a probe having a proximal end which tapers inwardly throughout its length to an angled distal end for purposes of concentrating the high intensity light.
Other light guides and probes are disclosed in German Published Patent Application No. DE 2507601 A1 and by U.S. Pat. Nos. 4,792,692 and 4,723,825 issued to Herold et al.; 4,836,782 issued to Gonser; 4,076,378 issued to Cole; 2,945,958 issued to Morris; 5,412,749 issued to Sayegh et al.; 5,495,541 issued to Murray et al.; 4,688,884 issued to Scifres et al.; 4,697,867 issued to Blanc et al.; 4,332,439 issued to Lxc3xcbbers et al.; and 6,208,788 issued to Nosov.
While the aforementioned light guides and methods of their manufacture may be satisfactory for their intended purposes, there is a need for a fiberoptic probe having a tapered section which can be efficiently manufactured and which can be utilized to concentrate high intensity light. To this end, the method of making the probe should not require the complicated and expensive step of heating a fused fiberoptic rod along substantially its entire length within an expensive furnace apparatus to stretch the rod and provide the rod with a relatively long and continuous taper. Rather, the tapered section of the probe should be restricted to a relatively small section of the distal tip of the probe while the remaining sections of the probe remains at a substantially constant unmodified diameter throughout. In addition, preferably the probe made by the method should have a novel configuration which permits a concentrated high intensity light to be accurately directed within a mouth of a patient during a dental procedure.
With the foregoing in mind, a primary object of the present invention is to provide a method of making a fiberoptic light guide having a distal end with a relatively short-length tapered tip.
Another object of the present invention is to provide a method of efficiently stretching a fused fiberoptic rod without the need of an expensive furnace and heating element and complicated heating and stretching process.
A further object of the present invention is to provide a method of making a fiberoptic dental light probe which has a substantially constant diameter except for a relatively small section of an angled distal end of the probe.
A still further object of the present invention is to provide a dental fiberoptic dental light probe having a unique configuration which concentrates high intensity light and permits accurate direction of the light toward a photocurable resin within the mouth of a patient during a dental procedure.
More specifically, the present invention provides a method of making a fiberoptic light guide that includes the step of supporting in a vertically-disposed position an elongate fused fiberoptic rod having opposite ends and a mid-section located therebetween. Thereafter, only the mid-section of the elongate fused fiberoptic rod is heated to soften the mid-section such that the mid-section thins and elongates under its own weight by the force of gravity. The heating step is discontinued when the fused rod elongates to a predetermined length to prevent the mid-section from further stretching and to permit the mid-section to cool. After the mid-section cools, it is cut at the thinned and stretched area of the mid-section to provide a pair of separate, substantially-identical, fiberoptic light guides each having a tapered distal tip.
Preferably, the method is utilized to make a fiberoptic dental light probe and further includes the initial steps of inserting a bundle of optic fibers into a hollow cladding having a predetermined outer diameter, heating the cladding and optic fibers, and drawing the cladding and optic fibers to fuse the bundle of optic fibers together and to seal the bundle of optic fibers within the cladding thereby forming an elongate, substantially cylindrical fused fiberoptic rod. The fused fiberoptic rod has an outer diameter less than the predetermined outer diameter of the pre-drawn cladding and is thereafter supported in a vertically-disposed depending position from a rotation device and rotated about its central longitudinal axis. The step of heating the mid-section is accomplished while the fused rod is supported and rotated by the rotation device by a small high temperature flame directed in a transverse direction at the fused rod from a gas fired blow torch. After the fused rod is cut at the stretched and thinned midsection, preferably the probes produced therefrom are bent to form angled distal ends and preferably the ends are cut to size, ground and polished.
According to another aspect of the present invention, a fiberoptic dental light probe is provided. The probe has a light guide body made from a single continuous fused fiberoptic rod having an outer cladding which provides a seal for a bundle of fused optic fibers. The body has an elongate cylindrical proximal end, a distal end having a tapered tip, and an arcuate section interconnecting the proximal and distal ends. The elongate proximal end has a substantially constant diameter throughout its length, and the arcuate section and distal end each have a diameter substantially equal to that of the proximal end except at the tapered tip of the distal end which is reduced in diameter. Preferably, the tapered tip is limited to about a 10 mm length of the distal end and tapers at an angle of about 15xc2x0 from a central longitudinal axis extending through the distal end. In addition, preferably the diameter of the proximal end, arcuate section, and distal end is about 13 mm except at the tapered tip which tapers to an end surface with a diameter of about 8 mm.